CD274 and esophageal squamous cell carcinoma: Nine trials were included in this analysis: CheckMate-648,1 ESCORT-1st,2 KEYNOTE-590,3 ORIENT-15,4 KEYNOTE-181,5 ESCORT,6 RATIONALE-302,7 ATTRACTION-3,8 and ORIENT-2.9 Six trials (CheckMate-648,1 ESCORT,6 KEYNOTE-181,5 KEYNOTE-590,3 ORIENT-15,4 and ORIENT-29) reported HRs but not KM curves for the subgroup of patients with ESCC with low PD-L1 expression.